As is known in the gas turbine engine field of technology, air swirlers utilized on fuel nozzles in the combustor of a gas turbine engine is disposed in a hostile environment and is subjected to extremely high temperatures. Historically, air swirlers have had an erosion problem which has required sophisticated cooling techniques to resolve this problem. Since the advent of higher performance engines that require higher temperatures at the inlet of the turbine, the combustor is relegated to operate at higher temperatures. The increased temperature in the combustor has acerbated the erosion problem. Additionally, certain engine designs require that the swirler be offset from the center line of the combustor. This, orientation of the swirler poses unusual and difficult cooling problems which even under ordinary circumstances is an already difficult problem. Experience has shown that a 0.100 inch offset from the combustor's center line has evidenced erosion problems that would invariably prematurely erode one half of the swirler. The offset locates one side of the swirler closer to the cooler air and the other side is, obviously, further away, such that the localized heating on the side that is adjacent the hotter air causes severe erosion.
U.S. Pat. No. 4,584,834 granted to J.M. Koshoffer et al on Apr. 29, 1986 discloses a fuel nozzle/swirler combination which attempts to prevent heat streaks from occurring on the liner of the combustor. In this disclosure the fuel nozzle/swirler design includes means for controlling the discharge spray angle of the fuel air mixture in order to obviate the hot streaking problem. This invention is significantly different from the teachings of the 4,584,834 patent,supra, as it is not concerned with the mixture of the fuel/air, nor is it concerned with hot streaks directed toward the combustor's liner. This invention solves the problem incidental to the offsetting of the fuel nozzle from the combustor's center line to obviate erosion occasioned by the uneven cooling of the air swirlers.
We have found that by judiciously locating and orienting the admission cooling air hole to the swirler will distribute the cooling uniformly around the swirler and obviate the erosion problem alluded to in the above paragraph.